(1) Field of the Invention
The present invention relates to a lifter for Venetian blind, particularly a cord-lock mechanism to support the slats, and, take up or release a lift cord to raise or lower the slats.
(2) Description of the Prior Art
Each Venetian blind is composed of a plurality of vertical or horizontal slats running in parallel, the tilting of which can adjust indoor darkness and preserve confidence in personal living. It is being extensively used in offices and homes. The conventional horizontal Venetian blind being used can have its slats tilted and lifted, and comprises mainly a rectangular sectioned and non-rotary headrail, a foot rail, two or more ladders each including an outer ladder and an inner ladder suspending from the headrail to the foot rail to support a plurality of slats with a plurality of connecting tapes located between the outer and inner ladders, a tilter within the headrail and a transmission device therefor to tilt the slats, and a lifter to raise and lower the slats. The lifter is incorporated with a lift cord, at least two wires extending from the headrail to the foot rail and connected to the lift cord, and a pulley set. When the lift cord is pulled upwards, the pulley set causes the wires tied to the foot rail to displace upward simultaneously to raise the foot rail as well as all or part of the slats, and consequently cause the lower slats to close to the upper slats.
The conventional lifter for a Venetian blind is quite complicated in structure. Hence, its production cost is high. Moreover, it is hardly to implement mass production with automatic assembly process, and it indeed has the following defects:
(1) Such sophisticated lifter required assembly at factory, and its installation position can not be changed after it is assembled to satisfy the user's habit or environmental requirements. Production and use of which are hence inconvenient.
(2) In general the conventional lifter can not rotate the headrail directly, and to tilt the slats, the conventional tilter must includes worm drive, transmission shaft, bearings and gears to drive some ladder drums to rotate, and hence the structure of the conventional Venetian blind is very complicated and heavy, production cost of which is thus relatively high.
(3) In association with the conventional tilter, the conventional lifter requires a lot of sophisticated components and long transmission, and therefore in the cause of raising or lowering, the slats and the foot rail may become higher at one end and lower at the other end due to unbalanced force applied to the lift cord and extra long transmission, and in the most serious case the slats and the foot rail may be seized and can't be raised or lowered.